1. Field of the Invention
The present invention relates to a transmitting apparatus and method, and a receiving apparatus and method. More specifically, the present invention relates to a transmitting apparatus and method, and a receiving apparatus and method that provide low-delay data transmission with reduced unnecessary delay periods in a more stable manner irrespective of the network status.
2. Description of the Related Art
In recent years, the demand for low-delay transmission of multimedia data via the Internet or any other transmission path has increased. For example, applications for allowing an operator in a remote place to operate surgical instrument in the operating room while viewing the operating room scenes of a moving image transmitted from the operating room, called telesurgery applications, are available. In such applications, it is desirable that a moving image be transmitted with a delay less than a several frame interval in order to increase the operability of surgical instrument at a remote place.
In existing streaming methods, a transmitting apparatus notifies a receiving terminal of a buffering period or a parameter value necessary for calculating a buffering period by, for example, writing it in a transmission format or a signaling message, and the receiving terminal sets a buffering period in accordance with the obtained information.
Further, the virtual reference decoder of a type that characterizes the encoding rate and the buffer parameter using the so-called leaky bucket model and defines them as a set of parameters (R, B, F) has been proposed (see, for example, Jordi Ribas-Corbera, Member, IEEE, Philip A. Chou, Senior Member, IEEE, and Shankar L. Regunathan, “A Generalized Hypothetical Reference Decoder for H.264/AVC” IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY, VOL. 13, No. 7, JULY 2003), where R denotes the transmission rate, B denotes the buffer size, and F denotes the initial decoder buffer fullness (F/R is the start-up or initial buffer delay).
The initial buffer delay F/R is equivalent to the buffering period. When the transmitting apparatus smoothes the data rate to a transmission rate different from the encoding rate and transmits the resulting data by writing a plurality of sets of parameters (R, B, F), the receiving apparatus can decode and reproduce the data in a stable manner without causing buffer failure by specifying the buffer size corresponding to the transmission rate.